Question 1

Which of the following best describes the role of cyclin D1 and cdk4 at the G1-S restriction point in the cell cycle?

Accepted Answer

Cyclin D1 binds to cdk4, leading to phosphorylation of Rb protein, which releases E2F and allows transcription of S-phase genes.

Question 2

A mutation in the gene encoding phospholipase C would most directly disrupt which step in G-protein signaling?

Accepted Answer

The cleavage of PIP2 into DAG and IP3, preventing downstream calcium release and kinase activation.

Question 3

Which of the following best explains why the metaphase-anaphase checkpoint is critical for genomic stability?

Accepted Answer

It ensures that all chromosomes are properly attached to the spindle before sister chromatids separate, preventing aneuploidy.

Question 4

During translation, which of the following events occurs when a stop codon enters the A site of the ribosome?

Accepted Answer

A release factor binds, promoting hydrolysis of the polypeptide from the tRNA.

Question 5

A patient with a mutation in the gene encoding the ACE2 receptor would most likely show resistance to infection by which virus?

Accepted Answer

SARS-CoV-2, because the virus uses ACE2 as its entry receptor.

Question 6

Which of the following best describes the function of IP3 in G-protein coupled receptor signaling?

Accepted Answer

IP3 acts as a second messenger that binds to and opens calcium channels in the endoplasmic reticulum.

Question 7

Which of the following mutations would most likely result in a truncated, nonfunctional protein?

Accepted Answer

A nonsense mutation introducing a premature stop codon.

Question 8

Which method would you use to amplify a specific DNA sequence from a small sample for further analysis, and why?

Accepted Answer

Polymerase Chain Reaction (PCR), because it can exponentially amplify specific DNA regions using primers.

Question 9

Which of the following best describes the 'wobble hypothesis' in translation?

Accepted Answer

The third base of a codon can pair less stringently with the corresponding base of the tRNA anticodon, allowing some tRNAs to recognize multiple codons.

Question 10

A cell is exposed to a drug that blocks voltage-gated sodium channels. What is the most immediate effect on nerve conduction?

Accepted Answer

Action potentials cannot be generated, so nerve impulses fail to propagate.

Question 11

Which of the following best explains the difference between cis-acting and trans-acting elements in gene regulation?

Accepted Answer

Cis-acting elements are DNA sequences near the gene they regulate, while trans-acting elements are usually proteins that can act at a distance.

Question 12

Which of the following is a real-world application of CRISPR/Cas technology?

Accepted Answer

Editing the genome of human embryos to correct genetic diseases.

Question 13

Which of the following best describes the function of the ribosome during translation?

Accepted Answer

It catalyzes the formation of peptide bonds between amino acids as directed by the mRNA sequence.

Question 14

A cell with a nonfunctional E2F protein would most likely be unable to:

Accepted Answer

Transcribe genes required for S-phase entry.

Question 15

Which of the following best explains why a frameshift mutation is often more severe than a missense mutation?

Accepted Answer

A frameshift alters the reading frame, potentially changing every amino acid downstream and often introducing a premature stop codon.

Question 16

Which of the following best describes the role of calmodulin in G-protein signaling pathways?

Accepted Answer

Calmodulin binds calcium ions and activates protein kinases, leading to downstream cellular responses.

Question 17

Which of the following best explains why the G2-M checkpoint is important in the cell cycle?

Accepted Answer

It ensures that DNA replication is complete and checks for DNA damage before mitosis begins.

Question 18

Which of the following statements about the COVID-19 virus (SARS-CoV-2) is correct?

Accepted Answer

It is an RNA virus that enters host cells by binding its spike protein to the ACE2 receptor.

Question 19

Which of the following best describes the function of aminoacyl-tRNA synthetases?

Accepted Answer

They attach the correct amino acid to its corresponding tRNA, ensuring fidelity in translation.

Cell Biology Study Guide: Mitosis, Meiosis, Gene Regulation, Signal Transduction, and Methods

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